High durometer roofing shingles used to cover sloped roofs are known in the art. Typically, these roofing shingles are used to replace shingles, shakes, or other covering elements made of slate, wood, asphalt, or other hard, natural materials known in the art. These shingles are designed essentially to match the size, shape and texture of the shingle to be replaced, thereby maintaining essentially the same installation pattern, architectural perspective or aesthetic appearance for the roof on which they are placed.
Heretofore, polymer blends of vulcanized scrap rubber or ground rubber and polyolefin resin have consistently been employed to produce these high durometer roof covering elements. For example, U.S. Pat. Nos. 5,312,573 and 5,157,082 refer to processes for the production of useful articles made from reclaimed vulcanized rubber, preferably from tires, and polyolefin resins such as polyethylene or polypropylene. In each instance, the major component of the polymer blend is the inert vulcanized rubber.
More particularly, the inert vulcanized scrap rubber is often reclaimed from recycled tires, as noted hereinabove, or from off-specification rubber compounds available from tire manufacturing facilities or various other industrial facilities. Such rubber typically includes rubber materials such as natural rubber, synthetic polyisoprene, styrene butadiene rubber (SBR), polybutadiene, butyl rubber (IR) or the like or mixtures and blends thereof. While such rubber may be particularly useful for the processes developed in the above-mentioned patents, these rubbers are not easily converted into new products and must oftentimes be employed with additional polymeric ingredients and/or compatibilizers in order to form the articles desired. For example, both patents noted hereinabove require the use of additional thermoplastic resins such as polyethylene and polypropylene, or copolymers thereof.
Ethylene-propylene-diene (EPDM) terpolymers have gained wide acceptance in the construction industry as a suitable material for single-ply EPDM-based roofing membrane or sheeting compositions. To the extent that EPDM may be included in the scrap or ground vulcanized rubber products of the prior art, EPDM has not been used in significant portions and is essentially inert in the scrap rubber compositions, acting, for the most part, as a filler material since the rubber has already been cured. Nevertheless, single-ply EPDM-based roofing membrane or sheeting has rapidly gained acceptance as an effective covering and barrier to prevent the penetration of moisture through industrial and commercial flat roofs. Such EPDM membranes have outstanding weathering resistance, flexibility and low temperature properties. EPDM-based polymeric roofing compositions are normally prepared by vulcanizing or curing it in the presence of sulfur or sulfur-containing compounds, such as mercaptans. The use of EPDM is also advantageous in that it can be easily mixed with other ingredients, such as mineral fillers, processing oils and the like to provide a suitable single-ply polymeric roofing membrane composition. These membranes are typically applied to the roof surface in a vulcanized or cured state, but are flexible enough to be transported in the form of a roll. However, these membranes are not used on sloped roofs, would be difficult to install on sloped roofs, and do not possess the required hardness to be suitable for use on sloped roofs.
Traditional asphalt-based roofing shingles are well known, but typically do not weather well in cold temperatures. These traditional roofing shingles are also somewhat susceptible to damage by hail. Furthermore, it is known that roofing shingles of this type do not provide the heat aging, ozone, oxidation and moisture resistance of roofing membranes employing EPDM terpolymers. Slate roofing shingles, while suitable for most purposes, are very heavy and very expensive in comparison to asphalt or polymeric roofing shingles. Thus, neither of these alternatives, i.e., asphalt or slate roofing shingles are particularly desirable.
Roofing shingles of the type described hereinbelow are generally stiff, and can be molded into flat sheets of essentially any size or shape. Where the roofing shingle to be developed will replace slate or asphalt shingles, it has been found that production of a rectangular roofing shingle which is about 0.25 inches thick, about 18 inches long and about 12 inches wide, is desirable. It will be appreciated, however, that other sizes and shapes may be more suitable and preferred when used to replace shingles of other types or when the slate or asphaltbased shingles being replaced are not of that same general size or shape, and the present invention should not be limited thereto.
Accordingly, it is believed desirable to develop low cost, high durometer polymeric roofing shingles to replace traditional shingles, shakes or other covering elements made of slate, wood, asphalt, and the like. The roofing shingles should also impart improved burn resistivity, weathering resistance, stress-strain properties, die-C tear characteristics, Shore "A" hardness and protective properties over the traditional roofing shingles used to cover sloped roofs.
The resulting roofing shingle compositions of the present invention are seen as being useful to the manufacture of high durometer roofing shingles, suitable as a replacement for traditional roofing shingles used to cover sloped roofs, where aesthetic appearance, improved burn resistivity, resistant to hail and wind damage and weathering performance are some of the more desirable characteristics of roofing shingles.